Significant quantities of waste, including nuclear, industrial and/or chemical waste, are currently being stored at various locations throughout the United States and in other countries. The waste is typically stored in large tanks, such as large underground storage tanks (“USTs”). Much of this waste has been sequestered in USTs for a long time. Leakage or other undesirable release of waste materials, for example due to degradation of the USTs, seismic or other natural events, or from human error or deliberate actions, is an ongoing concern for such USTs.
The processing of nuclear materials for weapons production, for example, has generated residual wastes that are toxic, corrosive, and contain radioactive materials that have been stored in shielded and/or underground storage tanks. By one counting, the Department of Energy has 332 USTs that are being used to store radioactive and chemical mixed waste generated from weapon materials production, including over 100 million gallons of high-level and low-level waste. The handling of this waste material is complicated and difficult due to safety considerations and a desire to avoid or minimize adding to the waste inventory.
Processing or otherwise handling the waste requires a containment system that ensures no waste materials are released to the environment. To prevent any aerosol releases from USTs during normal operations, USTs usually have atmosphere containment systems wherein any gas or vapor release from the tank passes through an HEPA based filtering system.
The liquid portion of the stored waste presents a particular risk because any breach of the tank containment has the potential to release chemically and/or radiologically active liquid into the environment which can spread over a wide area due to the mobility of liquids. Reducing the liquid content of waste materials within a tank reduces the risks associated with leakage. In addition, concentrating the waste by removing clean water as evaporated condensate reduces the volume of the waste material, and therefore reduces the total tank volume required for containing the waste materials.
Of course, processing the waste materials, for example by reducing the liquid content of the stored materials in these tanks, raises safety issues associated with the hazardous nature of the materials. For example, the personnel exposure to risk must be kept as low as is reasonably achievable. In addition, the risk of releasing waste materials in various accident scenarios must be minimized. There is a need, therefore, for a system capable of processing materials in USTs, for example by reducing the volume of the materials and/or moving the waste to different storage facilities, in a safe and reliable manner.